The present invention has its genesis in the consideration of the economics of mining iron ore. There are considerable variations in the types of materials that are in deposits that contain iron ore. The materials are generally in the form of particles and include, by way of example, any one or more of the following types of materials: magnetite, hematite, goethite (vitreous and limonitic), clays, shale, and chert.
An important issue for mine operators is to produce a marketable product or range of products. Marketable products include products that have specified minimum amounts of iron in the products. Marketable products may be blends of any one or more of magnetites, hematites, and goethites sourced from pits in one iron ore deposit or multiple iron ore deposits.
It is known to mine iron ore in large blocks of the ore. In accordance with known mining method, a block of ore, for example 40 m long and 20 m wide by 10 m high and containing 8,000 tons of ore, is analysed for example by chemically analysing samples taken from drill holes in the block that determine, on average whether the ore is (a) high grade, (b) low grade, or (c) waste material. The cut-off between high and low grades is dependent on a range of factors and may vary from mine to mine and in different sections of mines. The block of ore is mined, picked up from a mine pit and transported from the mine pit. The ore is processed inside and outside the mine pit depending on the grade determination. For example, waste ore is used as mine fill, low grade ore is stockpiled or used to blend with high grade ore, and high grade ore is processed further as required to form the marketable product. Accordingly being able to sort bulk granular iron ore into for example the above grades can enhance the economics of the mine.
While the above background and the following description focuses on iron ore as an example of particulate matter it is emphasised that the present invention is not confined in application to iron ore. Moreover, it is also emphasised that the present invention is not confined to particulate matter in the form of bulk granular materials.